You can see when you are using data by looking at data usage details under your current usage. It lists how much data was used and at what time so you can narrow down what may be consuming your data. I looked and discovered that one of the teens on my line is using huge amounts of data when he is at his dad's every other weekend when he has no access to wifi. My question is what can he possibly be doing that would use .75 - 1GB of data at a time???